1. Field of the Invention
The present invention relates to printer drivers. In particular, the present invention relates to a client/server printer driver system useful for carrying out print jobs on Network Computers ("NCs"), network appliances, and other non PC devices capable of printing.
2. Background of the Invention
Network Computers are small computers that are connected to a local area network ("LAN") or to the Internet and contain significant local processing intelligence. Such NCs are capable of running applications that are either downloaded from the LAN or Internet or are loaded from unalterable local storage (e.g., read-only CD-ROM). NCs generally have no local permanent storage, instead storing information remotely. Thus, NCs are highly dependent on the network. Furthermore, NCs are characterized by the usage of nontraditional operating systems, often using television monitors for displays and having limited local capabilities. The presently contemplated target markets for NCs are:
Home--Designed for ease of use, novice customers PA1 Education--Permits less expensive solution than traditional PC's with more control PA1 Business--Less expensive connections and more control at server/MIS level
Similarly, network appliances (such as Internet telephones, etc.) are special-purpose devices that contain computing capability and may connect to a centralized server, LAN, or the Internet.
Traditional Personal Computer ("PC") printer drivers are designed to be used on the PC where the application that is generating the print request resides. One sample driver system is shown in FIG. 1. The application 130 converts the desired print data into GDI 132 or other text commands and graphics primitives with associated page positions and/or forms controls. The print job may be spooled 150 (i.e., stored) to allow the user to resume working with the application 130. These commands may be formatted by the driver 100 into a recognizable industry defined data definition (e.g. PCL) or the printer driver 100 may use the application 130 and/or platform intermediate commands (e.g., Microsoft Windows.TM. GDI primitives) and act on these commands to create internal direct printer commands 170 to control the printer hardware 120. The printer does not necessarily need to be physically attached to the PC 110 where the application 130 and driver 100 reside, but may be remotely located such as on a LAN network (not shown).
One benefit of having a PC-side printer driver system is the movement of the processing into the PC itself (rather than at the printer), thereby permitting more flexibility and control. Another benefit of this system is that more advanced functions are possible by using a more powerful host PC, while permitting cost minimization of the printer hardware itself.
As one tries to fit the traditional host based printer driver models into the Network Computer model (as shown in FIG. 2), there are problems that result from limitations of the NC. Problems with current solutions in NC environments stem from the fact that NC devices have only a very limited amount of random access memory ("RAM") and no permanent storage (to allow them to achieve their minimal cost targets). In contrast, almost all standard PC printer drivers use local spooling to the local permanent storage. This is generally not possible with an NC. Also with small amounts of local RAM, 4 MB typically, there is often insufficient memory for the driver, application, and print data, especially if there are color bitmaps or complex graphics images to be printed. Also, many of the NC devices that are being developed today have different operating systems and have different API and/or GDI interface definitions which makes developing a printer driver extremely cumbersome. Thus, the additional platform support requires generation of new software drivers.
Traditional printing implementations on NCs 210 (FIG. 2) have followed the standard printing model. For instance, in the NC system, a server 200 is used to load applications 130, communicate with the network, and store data needed by the NC 210. The NC 210 itself runs the application 130 which might request printing. The other implementation details are the same as in the standard printing model for PCs (see FIG. 1).
The benefits of this traditional NC printing model are 1) its similarity to current driver models and 2) that GUI models are known by platform already. However, the NC system raises the following drawbacks of this printing model. There are severe memory and graphics limits on NCs. Also, NC hardware differences present unique issues with respect to operation of software thereon and the hardware which may be connected to an NC. Also, the traditional spooling system may be unacceptable where the NC is limited in storage space and/or memory and, therefore, potentially unable to handle even modest size print jobs, especially those containing significant amounts of graphical data. This printing system does not work with NCs that have minimal RAM.